PIN TUMBLER CYLINDER LOCK WITH SHEARABLE ASSEMBLY PINS AND METHOD AND APPARATUS OF MANUFACTURE

Abstract: A turnable lock cylinder (10) operable with driver (15u) und tumbler (15l) pins when positioned by a key (16) at a shear line (18) in which shearable assembly pins (15a-e) are assembled in the cylinder (10) and thereafter sheared to form such driver (15u) and tumbler (15l) pins for operation thereon. Each assembly pin (15a-e) is selectively weakened at a plurality of locations (17a-h) which correspond with notched depth heights of the family of keys capable of insertion in the keyhole. Such weakening (17a-h) is controlled so that pin shearing can be accomplished by application of rotational or linear forces applied to any part of the cylinder (10) except the key (16).

Description: PIN TUMBLER CYLINDER LOCK WITH SHEARABLE ASSEMBLY PINS AND METHOD AND APPARATUS OF MANUFACTURE Background of the Invention Prior cylinder locks have included a plurality of tumbler pins and aligned driver pins urged by springs against the key. The pins are separately manufactured to selected lengths prior to lock assembly. It has also been proposed to install one-piece pins in a cylinder; accomplish selected elevation of the pins using a notched key and thereafter shearing each pin, as held in such elevation by the notched key, into two lock pins (U. S. Patent No. 1,953,535) . Such prior method has the disadvantage that any second randomly-selected insertable key would be capable of elevating the pins and, if torqued, would again shear the pins thus compromising security. Summary of the Invention Broadly, the present invention comprises a cylinder having a body, a turnable plug, a shear line therebetween, a plurality of selectively weakened assembly pins for initial positioning by a notched key. The assembly pins are sheared by the manufacturer or locksmith using special machinery to thereafter function as both driver and tumbler pins. Such assembly pins are strong enough so that torquing or otherwise forcing with an insertable key by the lock user or person with an unauthorized key or similar tool will not shear them. It is a feature of the invention that the assembly pins have a plurality of selectively weakened portions to control shearings at selected points provided sufficient shearing force is applied. It is a feature that the driver and tumbler pins though sufficiently weakened are strong enough so that torquing of a key by hand or with a tool will cause the key or tool to fail before the pins shear. Brief Description of the Drawings Fig. 1 is a side elevational cutaway view of the lock of the present invention including shell, plug and key-positioned assembly pins; Fig. 2 is a side elevational view of an assembly pin of the present .invention; Fig. 3 is a view similar to Fig. 1 in which the pins have been sheared by relative lateral movement between the shell and plug; Fig. 4 is a plan view of the apparatus for shearing assembly pins and crimping the shell and plug together; Fig. 5 is an elevational view of the apparatus of Fig. 4; Fig. 6 is a partial sectional view along line 6-6 of Fig. 3; Fig. 7 is a partial sectional view along line 7-7 of Fig. 6; Fig. 8 is an elevational view of the pin of a second embodiment; Fig. 8a is an enlarged view of a pin groove B of the pin of Fig. 8; Fig. 9 is a sectional view perpendicular to the horizontal axis of the plug without pins; Fig. 9a is a sectional view similar to Fig. 9 with pins and with the plug slightly turned; Fig. 10 is a plan view of a second shearing mechanism with longitudinal axis A-A for use at retail locations; and Fig. 11 is a sectional view through longitudinal axis A-A of the mechanism of Fig. 10. Description of the Preferred Embodiment In Figs. 1-3, lock 10 includes cylinder shell 11 with plug collar 13c, turnable cylinder plug 13, five (5) vertical pin passageways I4a-e extending up into housing 11 and down into plug 13. Also shown are assembly pins 15a-e, plug tail 12, brass key 16, cylinder shear line 18 and pin springs 20a- e. Each assembly pin 15a-e has eight (8) circumferential grooves 17a-h. Pins 15a-e are made of selected material and their grooves 17a-h are shaped and proportioned to accomplish assembly pin searing by the manufacturer or locksmith while preventing compromise in security while the lock is in service through use of an unauthorized key or other instrument. Different manufacturers have differing non-notch key configurations which allow the keys of a given manufacturer to be insertable in locks of that manufacturer. Assembly pins of the invention are notched or otherwise selectively weakened to reduce the force taken to shear such pins; however, they are not weakened such that an insertable key (a key with the same keyway configuration on the lock key) with a different cut could be torqued by hand or by a tool to cause the driver and tumbler pins to shear prior to key or tool failure. The pin notches have a depth and shape such that only the force of factory or locksmith equipment applied to portions of the plug, and not applied to the key, can shear the 1 pins. Forces applied to the key or directly to plug collar 13c in a direction parallel to the axis of rotation of plug 13 are resisted and absorbed by collar 13c engaging shell 11. The following assembly pins, with varying notch diameters, were tested: Inner Notch Average Force Per Diameter Pin To Shear 0.060 inch 95 lbs. 0.062 inch 105 lbs. 0.065 inch 120 lbs. 0.070 inch 140 lbs. 0.074 inch 155 lbs. 0.079 inch 180 lbs. 0.084 inch 205 lbs. Inner notch diameter (ND) was less than overall diameter or outer notch diameter D (see Fig. 2) . An inner diameter of 0.062 inch is preferred for padlock pins. In the above tests D was 0.094 inch. Notch angle (C) was 20° (degrees) (Fig. 2) . The ratio of ND to D is preferably in the range 63%-74%. The present invention also includes door hardware pins where an inner diameter of 0.074 inch is preferred for pins having an outside diameter (D) of 0.114 inch. In the manufacture of cylinder 10, assembly pins 15a-e, each with eight (8) weakening circumferential grooves 17a-h, are fabricated for use in making a quantity of locks. In the present system, preferably keys have eight (8) different cut depths and five pin cylinders, creating thirty-two thousand (32,000) combinations. Each groove 17a-h has a width w (Fig. 2) of about .0060-0.010 inches and series of grooves 17a-h are spaced vertically (as shown in Fig. 2) about 0.0156 inch apart. In the assembly of cylinder 10, assembly pins 15a-e (each of which is the same within a tolerance of + 0.0005) are placed into passageways 14a-e and then sheared. The series of spaced-apart grooves 17a-h are located in the assembly pins 15a-e such that they are positioned at the shear line 18 by a family of insertable keys. Fig. 3 illustrates plug 13 being driven to the right to shear pins 15a-e as further explained below. As sheared, each assembly pin 15a-e breaks into an upper drive section 15u to function as a drive pin and aligned lower tumbler section 151 to function as a tumbler pin. Cylinder shell 11 has end ring portion 20 and plug 13 has angled portion 13a (Fig. 1) . A segment 2Op of ring portion 20 is crimped against portion 13a as later described (see also Figs. 6 and 7) . Turning to Figs. 4-5, pin shearing and crimping apparatus 30 includes lock fixture 31 having configured aperture 32. Cylinder unit 10 with its shell 11 and plug 13 and unsheared assembly pin 15a-e is placed in aperture 32 with housing 11 abutting wall 32w. Plug tail 12 is engageable with shiftable shear pin 41. Shift shear pin 41 is shown in its rest position biased to the right as viewed in Fig. 4 by spring 52. Also included in apparatus 30 is shearing plunger 36 mounted in cylindrical opening 37 of stationary mount block 38 spaced from fixture 31. Apparatus 30 further includes a crimper unit 50 including a crimping ram 52 driven by a solenoid unit (E) . Crimp shift pin 54 is shown in its rest position biased away from the cylinder shell 10 by crimp pin spring 55. In operation, cylinder 10 including shell 11, plug 13 plug tail 12 and key 16, as an assembly are placed in aperture 32 of fixture 31. Shear pin 41 is hit by shearing plunger 36 to apply force F to cylinder plug tail 12 to move plug 13 in direction A. Pins 15a-e are thereby sheared (Fig. 3) . Plug 13 is pushed back by hand using key 16 to the original position. Next, crimper unit 50 drives crimp shift pin 54 to crimp ring portion segment 20p of shell 11 against plug portion 13a (see Figs. 1, 6 and 7) . Turning to Figs. 8-10, a further embodiment of the invention is shown in which pins have a certain notch configuration and the plug is shaped to facilitate shearing and rotation. Each pin 60 of this embodiment has grooves or notches 61, for example, the ten (10) circumferential grooves 61-A-J (shown in fig. 8) . Each groove 61 has beveled surface areas or chamfers 63 to facilitate plug rotation and to make picking of the lock more difficult. Each chamfer 63 is sloped at angle C to the plane perpendicular to pin 60' s longitudinal axis (Fig. 8a) . The slope of chamfer 63 is parallel to tangent line T which is perpendicular to radius R (Fig. 9) . The selection of such a chamfer slope optimizes the ease of plug rotation. Distances from the bottom key-engaged end 60b of pin 60 to the center of each groove is set out in Table 1 (see also Fig. 8) . Table 1 Letter Distance in Inches A .166 B .181 C .196 D .211 E .226 F .241 G .256 H .271 I .286 J .301 Each notch A-J is comprised of a portion of a notch b above plane Z perpendicular to longitudinal pin axis LA and a notch portion b below line Z. Plug 64 of shell-plug unit 65 has a flat surface 66 positioned adjacent the upper shell section 67 of shell 57. After shearing, and with the key (not shown) inserted, the tumbler pin 60t is raised which in turn raises the driver pin 60d. As plug 64 is turned in either direction (such as direction A; Fig. 9a) , groove chamfer surfaces 63 assist in free turning when the tumbler pin 60t is too high or the bottom of the driver pin 60d too low. Chamfer surfaces 63 reduce the likelihood that pins will catch the sides of pin passageways 71u, 711 in either shell or in the plug. Turning to Figs. 10 and 11, a pin shearing mechanism 78 is shown having body 79, housing cavity 81, a turnable drive unit 82 mounted in cavity 81 for rotation about a horizontal axis (H) (Fig. 11) . Turnable unit 82 includes hand wheel 83 and nut 84 mounted in rotatable drive body 80. Nut 84 is turnable by wrench 86 (not shown) . As drive unit 82 is turned it translates plunger 87 through mating threads 88 on unit 82 and threads 89 on plunger 87. . Plunger 87 moves linearly in direction AA. Plunger 87 is held from turning by indentation 91 having flat surface 92 and by vertical post 93 which engages surface 92 to prevent rotation. Mechanism 78 includes lock holder recess 93 including shell support wall 94 which holds the shell plug unit 65 against translation in direction AA. In the operation of mechanism 78 (unit 65 is not shown in Fig. 10), the lock unit 65 is placed in holder recess 93, plunger 87 is advanced until it touches the plug 64 and a wrench is then used to turn nut 84 to translate plug 64 relative to its shell until the assembly pins 60 shear. Example A door lock constructed of five (5) assembly pin passageways 71 and assembly pins 60 which will, as explained, be sheared to form each pin set (a tumbler pin 70t and driver pin 70d in tandem) . Each assembly pin 60 has a basic diameter (BD) of .114 inches and a reduced weakened diameter (WD) in the grooves of .076 inches (see Fig. 8). Each assembly pin 60 has ten (10) grooves 61A-61J prior to shearing to create the tumbler-driver pin sets. Prior to shearing the door lock cylinder is shipped to a locksmith. A customer of the locksmith provides the locksmith with a key used by the customer in operating other lock of the customer. The locksmith inserts the customer's key in the lock, places the lock in the mechanism 78 and shears the assembly pins 60. The customer then installs the door lock in his home which lock can be served by the customer's existing key. Table 2 Pin Characteristics Basic Weakened In Line F Torque To Tvpe Diameter Diameter To Shear Shear (BD) (WD) Padlock .094 in. .076 in. 210 lb. 200 in lb. Door Lock .114 in. .076 in. 210 lb. 200 in lb. The pin diameter of each of the grooves (WD) is selected to provide sufficient strength so that the assembly pins 60 will not fail when a key (or tool of cross section to permit penetration into the keyhole) is torqued. The key (or- tool) will fail through breaking, shearing or twisting before' the pins 60 shear. As an example, a hardened steel key was inserted into the keyhole of a lock of the present invention and a torque of 240 lb/in was applied to the key. The tool broke without shearing the pins 60. The pin grooves 61A-J are also shaped to create a fracture or shear surfaces on both tumbler and driver pins which are non-flat and which facilitate lock operation. Finally, grooves 61A-J are shaped so that upon fracturing during manufacture or customizing by a locksmith, tumbler and driver pins 70 having end configurations including chamfer surfaces 63 are formed which assist in plug rotation during subsequent operation.

Claims: I CLAIM : 1. In a cylinder lock having a shell, a turnable plug within the shell, a keyhole in the plug, a plurality of alignable pin passageways in the shell and the plug, assembly pins in the passageways shearable into upper pin sections and aligned lower pin sections,the improvement comprising a) series of spaced-apart weakening means in such assembly pins having longitudinal axes with such weakening means being positioned, shaped and configured such that i) the assembly pin will not shear when a key or tool is inserted in the keyhole and torqued by a selected force of a first magnitude; and ii) the assembly pins shear when a force of second magnitude which is larger than the first magnitude is applied. 2. The cylinder lock of claim 1 in which the weakening means is a notch having notch portions spanning in a plane perpendicular to the pin axis. 3. A method for manufacturing a cylinder having a shell, a turnable plug, a key which fails when torqued by application of a first force, a shear line between the shell and plug, a plurality of pin passageways and an insertable key with cut depths comprising the steps of a) assembling the shell and plug with selectively- weakened assembly pin in each passageway such that application of a second force equal to or less than the first force to the key will not shear such pins; and b) thereafter shearing each assembly pins by application of third force larger than the first force along the shear line to shear each pin into two pin sections. 4. Apparatus for causing relative movement between a shell and a plug of a lock shell and plug which form a shear line and has a plurality of pins across such shear line comprising holding means for restricting movement of the shell and shearing means for moving the plug a sufficient distance to shear the pins. 5. The apparatus of claim 4 having in addition crimping means to crimp the shell to the plug. 6. Apparatus for shearing a lock pin in a lock having a shell housing and a plug therein by application of a force parallel to the axis of the plug comprising a) a frame; b) a receiver recess in the frame to receive a cylinder unit comprising a shell and a plug, the receiver including shell holding means for holding stationary shell against movement during shearing; c) plug translation means for translating the plug while the shell is held, said plug translation means in turn comprising i) a plug engageable translation means for movement toward and against the plug; and ii) rotatable power means slidably connected to the translation means to translate the translation means against the plug to move the plug as the shell is held. 7. The lock cylinder of claim 1 in which the plug has a flat surface adjacent the intersection of the pin passageways.

Inventors: HANNEMAN ROBERT H, WAGNER JAMES G, HANNEMAN, ROBERT, H., WAGNER, JAMES, G.
Applicants: MASTER LOCK CO, MASTER LOCK COMPANY
Application year: 1994
Main classification: B23P19
IPC codes: E05B17, E05B27